The instant invention seeks to improve ultrasonic endodontic assemblies, and more particularly to simplify the clamping of the fine endodontic files which are used in root canal work, as described in the following patents: U.S. Pat. Nos. 4,229,168, Scholz, Jr., Oct. 21, 1980, 4,330,278, Martin, May 18, 1982, 4,505,676, Gonser, Mar. 19, 1985, 4,571,183, Nash, Feb. 18, 1986.